Sealing apparatus and method

ABSTRACT

An improved sealing apparatus ( 10, 110 ) for use in establishing a seal in an annulus ( 12,112 ) between a mandrel ( 18,118 ) and a bore wall ( 14,114 ) has an annular seal element ( 20,120 ) initially activateable between a first, retracted, configuration and a second, expanded, configuration. The seal element ( 20, 120 ) is disposed around a mandrel ( 18,118 ) and is free to move relative the mandrel ( 18,118 ) such that when the seal element ( 20,120 ) defines the second, expanded, configuration, pressurised fluid from the annulus ( 12;112 ) urges the seal element ( 20,120 ) radially outwards into sealing or enhanced sealing engagement with the bore wall ( 14,114 ).

FIELD OF THE INVENTION

This invention relates to an improved sealing apparatus and method for use in establishing a seal in an annulus between a mandrel and a bore wall. More particularly, but not exclusively, embodiments of the invention may take the form of a downhole packer for use in sealing a wellbore annulus.

BACKGROUND TO THE INVENTION

Sealing apparatus and methods are used in many industries where it is desired to isolate, seal off or otherwise control movement of fluid in a given environment. In the oil and gas industry for example, sealing devices known as packers are commonly used to seal the annulus between a production conduit or the like, and a bore wall or a surrounding casing or other tubular.

In some instances, one or more packer may be used to prevent undesired movement of fluid up or down the annulus in order to seal off the wellbore. In other instances, a number of packers may be used to create an isolated annular region which, amongst other things, permits isolation of a problematic formation or permits controlled production from, or access into, a selected region of a formation.

Known packers may comprise an elastomeric annular sealing element mounted on a mandrel and which is capable of being extended radially outwardly to engage, for example, the wall of a bore in which the packer is located, thus providing a seal in the annulus defined between the mandrel and the bore wall. In some instances, the seal element may be axially compressed, for example by a setting tool, to effect radial expansion. In other instances, a swelling elastomer may be used which, in use, swells in response to the presence of an activation medium present in the annulus.

While such packers are effective and may be used reliably in a number of applications, the high temperature and pressure differences experienced in a downhole environment place particularly high demands on the seal elements of the packer to maintain the seal with the bore wall, the successful maintenance of the seal often being of critical importance to the safe, reliable and economic operation of the wellbore.

Also, the bore wall is often non-cylindrical and may include irregular or large diameter sections where an area of the bore wall has collapsed or been washed out. It may be impossible to create a reliable seal in such a section using a conventional packer.

In view of the importance of maintaining the seal, packers are typically designed to apply large forces sufficient to overcome and resist the forces expected during deployment and in use. In some instances, however, the pressure difference acting across the seal element may be sufficient to cause extrusion of the seal element, thereby reducing seal performance or making activation more difficult or in more extreme cases risking failure of the seal. In other instances, the use of large applied activation forces may be prevented or restricted due to the possibility of damaging the surrounding bore wall or tubulars.

SUMMARY OF THE INVENTION

Aspects of the present invention may relate to a sealing apparatus and method for use in establishing a seal in an annulus between a mandrel and a bore wall.

According to a first aspect of the present invention, there is provided a sealing apparatus for use in establishing a seal in an annulus between a mandrel and a bore wall, the apparatus comprising:

a mandrel; and

a seal element disposed on the mandrel, the seal element configured to define a first configuration and a second, expanded, configuration,

the apparatus configured so that fluid from the annulus acts on the seal element to urge at least part of the seal element radially outwards into sealing or enhanced sealing engagement with the bore wall.

The apparatus may be configured so the fluid from the annulus acts on the seal element when the seal element is in the second configuration.

Beneficially, embodiments of the present invention permit the creation and/or maintenance of a seal across the annulus of a bore of greater diameter, without the requirement for the seal element itself to expand to full bore diameter. Moreover, in instances where the bore wall is non-cylindrical and/or includes irregular or large diameter sections, such as where an area of the bore wall has collapsed or been washed out, embodiments of the present invention may beneficially permit the creation and maintenance of a reliable seal.

In use, the apparatus may be run into a bore with the seal element defining a first, retracted, configuration. In the first configuration, the seal element may define a first volume. The seal element may then be initially activated from the first configuration to the second, expanded, configuration. In the second configuration, the seal element may define a second, larger, volume. In the second configuration, pressurised fluid from the annulus between the apparatus and the bore wall (the annulus fluid) may be utilised to provide a second stage activation in which the seal element is urged into a third configuration in sealing or enhanced sealing engagement with the bore wall. In particular, but not exclusively, the annulus fluid used to urge the seal element from the second configuration to the third configuration may comprise fluid from upstream of the restriction created by the seal element defining the second configuration.

Beneficially, embodiments of the present invention provide for an initial activation of the seal element and a second activation which utilises the pressurised fluid in the annulus—which may otherwise cause extrusion of the seal element, reduce seal performance, make activation more difficult or risk failure of the seal—to maintain or enhance the seal with the bore wall. Moreover, by utilising the pressurised fluid present in the annulus the use of applied activation forces—which may otherwise damage the surrounding bore wall or tubulars and increase the size and weight of the apparatus—may be obviated or reduced.

The seal element may be moveable relative to the mandrel.

The seal element may be radially moveably disposed on the mandrel.

In some embodiments, the seal element may be freely radially disposed on the mandrel. For example, in some embodiments the seal element may not be secured to the mandrel.

In other embodiments, the apparatus may be configured so that the seal element or a seal element portion may be temporarily secured to the mandrel. For example, a first portion of the seal element may be fixed relative to the mandrel and a second portion of the seal element may be movable relative to the mandrel. In use, the first, secured, portion of the seal element may be configured or arranged to provide a seal with the mandrel. The first portion of the seal element may comprise a first end portion of the seal element. The second portion of the seal element may comprise a second end portion of the seal element. Thus, in some embodiments the seal element may comprise a first secured end and a second free end which is free to move radially into engagement with the bore wall. The secured portion may then be released.

Any suitable temporary securement may be used to secure the seal element or seal element portion to the mandrel. For example, the seal element or seal element portion may be secured by a releasable bond, barrier or the like. Beneficially, this permits the seal element to be secured initially, and then subsequently released for radial movement when required. Thus, in some embodiments part or all of the seal element may initially be secured to the mandrel and then released to engage the bore wall.

The seal element may be of any suitable form or construction.

In particular embodiments, the seal element may comprise an annular seal element and the seal element may be disposed around the mandrel. However, other suitable forms may be used where appropriate. For example, the apparatus may comprise a plurality of seal elements extending around the mandrel, the plurality of seal elements forming the seal between the mandrel and the bore wall.

The seal element may be configured to expand in the presence of a selected activation medium. The activation medium may comprise a fluid. In particular embodiments, the fluid may comprise fluid from the annulus between the apparatus and the bore wall.

In particular embodiments, the seal element may comprise a material which swells in response to oil. For example, the seal element may comprise an oil-swellable material, such as an oil-swellable elastomer.

In other embodiments, the seal element may comprise a material which swells in response to water. For example, the seal element may comprise a water-swellable material, such as a water-swellable elastomer.

In use, the apparatus may be run into the bore, exposure of the seal element to the selected activation medium in the annulus fluid causing the seal element to expand from the first configuration to the second, expanded, configuration to provide the initial activation of the apparatus.

Initial activation of the seal element may be achieved without mechanical activation. For example, the initial activation of the seal element from the first configuration to the second configuration may be performed through exposure of the seal element to the activation medium.

In embodiments where part or all of the seal element is initially secured to the mandrel, the seal element may be released during or as a result of the initial activation. Beneficially, embodiments of the present invention may permit controlled activation, for example permitting delayed activation or swelling.

In some embodiments, a coating may be provided. The coating may for example provide variable and/or controlled swelling rate. The coating may comprise a thermally degrading coating, for example a coating which degrades on exposure to selected elevated temperatures as experienced downhole. Alternatively, or in addition, the coating may comprise a chemically degrading coating, for example a coating which degrades on exposure to selected downhole fluids.

As mentioned above, the apparatus may be configured so that the seal element is moveable relative to the mandrel. In particular embodiments, the apparatus may be configured so that, in the second configuration, the annulus fluid is directed between the seal element and the mandrel. For example, the apparatus may be configured so that the annulus fluid impinges on an inner circumferential surface of the seal element. Thus, the annulus fluid may be used to urge or push the seal element radially outwards into sealing or enhanced sealing engagement with the bore wall.

The apparatus may be configured to define a fluid-receiving chamber between the seal element and the mandrel. The fluid-receiving chamber may be present when the seal element is in the first, retracted, configuration. Alternatively, and in preferred embodiments, the fluid-receiving chamber may be formed when the seal element expands or moves from the first configuration to the second configuration. Beneficially, this allows the seal element to define a smaller diameter first configuration than would otherwise be possible where a fluid-receiving chamber is present during run-in. This may assist in preventing damage to the seal element during run-in, for example.

Any suitable means for permitting the pressurised annulus fluid to pass between the seal element and the mandrel may be provided. For example, the apparatus may comprise a fluid passage configured to permit the passage of the pressurised fluid between the seal element and the mandrel.

The fluid passage may comprise an axially-extending fluid passage. In particular embodiments, the apparatus may comprise a plurality of axially-extending passages.

The passage or passages may be of any suitable form. In particular embodiments, the passage or passages may of hemi-cylindrical form. Where a plurality of passages is provided, the passages may be arranged circumferentially

In use, the passage or passages may be arranged to provide at least some of the fluid communication to the fluid-receiving chamber, the pressurised annulus fluid passing through the passage or passages and impinging on the seal element forcing or assisting in urging the seal element into sealing or enhanced sealing engagement with the bore wall.

In some embodiments, the apparatus may be configured so that the seal element engages the bore wall in the second configuration. For example, and in preferred embodiments, the apparatus may be configured so that the seal element provides initial sealing engagement with the bore wall in the second configuration. In such embodiments, the seal element may be maintained in sealing engagement or urged into enhanced sealing engagement with the bore wall in the third configuration. Alternatively, the apparatus may be configured so that the seal element engages but does not sealingly engage the bore wall in the second configuration. In such embodiments, the seal element may be urged into sealing engagement with the bore wall in the third configuration.

In other embodiments, the apparatus may be configured so that the seal element does not engage the bore wall in the second configuration. In such embodiments, the seal element may sealingly engage the bore wall in the third configuration.

The apparatus may be configured to retain the third configuration. For example, the apparatus may be configured so as to be biased towards the third configuration.

The seal element may be configured to retain the third configuration. For example, the seal element may be configured so as to be biased towards the third configuration.

The seal element may be configured to assist in passage of the fluid between the seal element and the mandrel.

The seal element may comprise a recess, groove or flute. The recess, groove or flute may be configured to assist in passage of the fluid between the seal element and the mandrel. Moreover, the provision of one or more recess, groove or flute may beneficially increase the contact area between and/or the volume of fluid acting on the seal element.

The seal element may comprise a plurality of recesses, grooves or flutes. In particular embodiments, the seal element may comprise a plurality of circumferentially arranged recesses, grooves or flutes.

The apparatus may comprise at least one further seal member and, in particular but not exclusively, the further seal member may be configured to define a cup seal.

The or each further seal member may be of any suitable form or construction.

The or each further seal member may comprise at least one of: an elastomeric seal member; a compression seal member; a packing member; an expandable member; a swellable member; an oil-swellable member; a water-swellable member; an inflatable member, or any suitable style of seal member.

The apparatus may comprise a single further seal member. In particular embodiments, the apparatus may comprise a plurality of further seal members.

Where the apparatus comprises a plurality of seal members, the seal members may be of the same or different construction.

Bonding may be provided between the seal element and the at least one further seal member. For example, the seal element and at least one further seal member may together define a composite construction. Any suitable bonding or securement may be used. For example, the seal element and the at least one further seal member may be bonded or secured by an adhesive bond or the like.

In embodiments comprising a plurality of further seal members, bonding may be provided between the further seal members. Any suitable bonding or securement may be used. For example, the further seal members may be bonded or secured by an adhesive bond or the like.

The further seal members may be selected and/or arranged in order to provide selected properties to the apparatus. For example, one or more seal member may comprise a material of greater hardness than one or more other seal member. Beneficially, the provision of a seal member having greater hardness may assist in preventing or at least mitigating extrusion of a seal member and/or the seal element.

In embodiments where the further seal member comprises an expandable or swellable member, the further seal member may be configured to expand or swell at a different rate to that of the seal element. For example, the further seal member may comprise an expandable or swellable member configured to expand or swell at a slower rate than that of the seal element. Beneficially, utilising an expandable or swellable member as the further seal member adjacent to the seal element may reduce or mitigate differential forces between the seal element and the further seal member, which may otherwise act to split or separate the seal element and the further seal member.

The apparatus may be configured so that part of the further seal member, or where there are a plurality of further seal members one or more of the seal members, is secured to the mandrel. For example, a first portion of the seal member may be fixed relative to the mandrel and a second portion of the seal member may be movable relative to the mandrel. In use, the first, secured, portion of the seal member may be configured or arranged to provide a seal with the mandrel. The first portion of the seal member may comprise a first end portion of the seal member. The second portion of the seal member may comprise a second end portion of the seal member. Thus, in some embodiments the seal member may comprise a first secured end and a second free end which is free to move radially into engagement with the bore wall.

Any suitable securement may be used to secure the seal member portion to the mandrel. For example, the seal member or seal member portion may be secured by a bond, barrier or the like.

In other embodiments, the apparatus may be configured so that the further seal member or a seal member portion is temporarily secured to the mandrel. For example, a first portion of the seal member may be fixed relative to the mandrel and a second portion of the seal member may be movable relative to the mandrel. In use, the first, secured, portion of the seal member may be configured or arranged to provide a seal with the mandrel. The first portion of the seal member may comprise a first end portion of the seal member. The second portion of the seal element may comprise a second end portion of the seal member. Thus, in some embodiments the seal member may comprise a first secured end and a second free end which is free to move radially into engagement with the bore wall. The secured portion may then be released.

Any suitable temporary securement may be used. For example, the seal member or seal member portion may be secured by a releasable bond, barrier or the like. Beneficially, this permits the seal member to be secured initially, and then subsequently released for radial movement when required. Thus, in some embodiments part or all of the seal member may initially be secured to the mandrel and then released to engage the bore wall.

The further seal member, or where the apparatus comprises a plurality of further members at least one of the further seal members, may comprise a recess, groove or flute. The recess, groove or flute may be configured to assist in passage of the fluid between the seal member and the mandrel. Moreover, the provision of one or more recess, groove or flute may beneficially increase the contact area between and/or the volume of fluid acting on the further seal member.

The further seal member, or where the apparatus comprises a plurality of further seal members at least one of the further seal members, may comprise a plurality of recesses, grooves or flutes. In particular embodiments, the further seal member may comprise a plurality of circumferentially arranged recesses, grooves or flutes.

In use, the seal element may be used to activate the further seal member or members. For example, the further seal member may be at least partially activated by expansion of the seal element from the first configuration to the second configuration. Alternatively, or additionally, the further seal member may be at least partially activated when the seal element is urged from the second configuration to the third configuration.

A ramp interface may be provided between the seal element and the adjacent further seal member.

The apparatus may be configured so that the further seal member, or where the apparatus comprises a plurality of further seal members at least one of the further seal members, is plastically deformed. For example, the further seal member adjacent to the seal element may be plastically deformed. Beneficially, this may assist in retaining the form of the extended seal in the event of loss of pressure differential.

One or more additional seal member may be provided. The one or more additional seal member may be of any suitable form and construction. The one or more additional seal member may be annular. In particular embodiments, the one or more additional seal member may comprise an o-ring.

In use, the seal element and the at least one additional seal member may together provide the respective seals with the bore wall and the mandrel.

The one or more additional seal member may be provided in a housing. A housing may be provided for each additional seal member. Alternatively, a plurality of additional seal members may be provided in a single housing. The housing or housings may be annular. The housing or housings may be interposed between the seal element and an end ring.

The apparatus may comprise one or more end ring, and in particular embodiments the apparatus comprises two end rings disposed at opposing ends of the apparatus. In particular embodiments, the fluid passage may be formed or otherwise provided in one of the end rings, for example around an inner circumferential surface of the end ring.

At least one end ring may comprise a radially-extending bore for receiving a retainer and, in particular embodiments, each end ring may comprise a plurality of radially-extending bores, each for receiving a retainer, such as a grub screw, bolt or the like. In use, the retainer or retainers may be used to secure the end ring to the mandrel.

The apparatus may be configured so that part of the annulus fluid also acts towards retaining the seal element and/or one or more seal member on the mandrel. For example, a component of the force generated by the annulus fluid may be directed radially inwards and so may assist in maintaining a seal element or seal member on the mandrel.

In use, embodiments of the present invention may utilise fluid pressure both to urge the sealing element into sealing or enhanced sealing engagement with the bore wall and also to retain the sealing element on the mandrel. The apparatus may be configured so that the fluid pressure impinges on selected areas, the selected areas configured to provide the required forces to urge the seal element radially outwards to provide sealing or enhanced sealing engagement with the bore wall and radially inwards to assist in maintaining the seal element on the mandrel.

The apparatus may comprise a back-up assembly for supporting the seal element in maintaining sealing engagement with the bore wall. The back-up assembly may comprise at least one of: a ring member; a support member arranged to extend over at least an end of the seal element; and a collar having a seal-engaging surface arranged to engage the end of the seal element, the collar interposed between the end of the seal element and the support member. The back-up assembly may comprise one or more layer of petals. For example, the back-up assembly may comprise a plurality of overlapping layers of petals. Beneficially, the provision of overlapping petals may prevent or mitigate extrusion of the seal element or seal members.

The apparatus may comprise a downhole packer.

The apparatus may comprise a uni-directional downhole packer. For example, the apparatus may be configured to be activated by the annulus fluid or differential fluid pressure acting in a selected direction.

The apparatus may comprise a uni-directional cup seal packer.

A ramp interface may be provided between the gauge ring and the seal element.

The end ring may comprise a tapered surface.

The seal element may comprise a tapered surface.

In use, the tapered surfaces of the end ring may define a ramp surface to assist in directing expansion and/or radial movement of the seal element.

The seal element and the further seal members may be disposed in overlapping relationship. For example, an uphole end of the first further seal member may axially overlap a downhole end of the seal element.

It will be understood that the seal element and, where applicable, the at least one further seal member may be of any suitable length. By way of example, where the seal element and the further seal member together define a length of 10 feet, 1 foot of the further seal member may be directly bonded to the mandrel and the back-up assembly may extend for 2 feet around the outside of the further seal member. In use, the seal element may expand or swell to engage the bore wall, thereby providing the initial activation. When pressure is applied, the remaining non-bonded portion of the further seal member is free to be pushed radially outwards and axially towards the back-up assembly end of the apparatus, forming or supplementing the seal.

According to a further aspect of the present invention, there is provided a method comprising:

providing an apparatus comprising a mandrel and a seal element for establishing a seal in an annulus between the mandrel and a wall of a bore;

disposing the apparatus in the bore;

activating the seal element from a first configuration to a second, expanded, configuration; and

urging at least part of the seal element radially outwards into sealing engagement or enhanced sealing engagement with the wall of the bore using fluid from the annulus between the mandrel and the wall of the bore.

The seal element may define a third configuration when urged into sealing or enhanced sealing engagement with the wall of the bore.

It should be understood that the features defined above in accordance with any aspect of the present invention or below in relation to any specific embodiment of the invention may be utilised, either alone or in combination, with any other defined feature, in any other aspect or embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is an end view of a sealing apparatus according to a first embodiment of the present invention;

FIG. 2 is a longitudinal section view of section A-A of FIG. 1;

FIG. 3 shows the sealing apparatus of FIGS. 1 and 2 in a first configuration in a bore;

FIG. 4 shows the sealing apparatus of FIGS. 1 and 2 in a second configuration in the bore;

FIG. 5 shows the sealing apparatus of FIGS. 1 and 2 in a third configuration in the bore;

FIG. 6 is an end view of a sealing apparatus according to a second embodiment of the present invention;

FIG. 7 is a longitudinal section view of section B-B of FIG. 6;

FIG. 8 shows the sealing apparatus of FIGS. 6 and 7 in a first configuration in a bore;

FIG. 9 shows the sealing apparatus of FIG. 6 and in a second configuration in the bore; and

FIG. 10 shows the sealing apparatus of FIGS. 6 and 7, in a third configuration in the bore.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring first to FIGS. 1 to 5, there is shown a sealing apparatus 10 according to a first embodiment of the present invention, the apparatus 10 in the illustrated embodiment comprising a downhole cup seal packer for use in sealing an open or uncased hole.

In use, the apparatus 10 establishes a seal in an annulus 12 (shown in FIG. 2 and in FIGS. 3 to 5) between the apparatus 10 and a wall (shown diagrammatically at 14 in FIG. 2 and in FIGS. 3 to 5) of a bore (shown diagrammatically at 16 in FIG. 2 and in FIGS. 3 to 5) which prevents passage of fluid along the annulus 12 in a selected direction, for example preventing passage of fluid in an uphole direction or in a downhole direction.

As shown in FIG. 1, the apparatus 10 comprises a mandrel 18 which forms part of a tubing string such as production conduit or the like (not shown). However, in order to show the other components of the apparatus 10, the mandrel 18 is not shown in FIGS. 2 to 5.

An annular seal element 20 is disposed around the mandrel 18, the seal element 20 comprising a swellable seal element which swells in response to a selected activation fluid in the annulus 12. In the illustrated embodiment, the seal element 20 is constructed from an oil-swellable elastomer and, in use, the seal element 20 may be run into the bore 18 in a first, retracted, configuration (as shown in FIG. 3) before being initially activated from the first configuration to a second, expanded, configuration when exposed to oil in the annulus 12 (as shown in FIG. 4).

The seal element 20 is disposed around the mandrel and is free to move relative to the mandrel 18 such that, in use, when the seal element 20 moves to the second configuration a fluid-receiving chamber C is defined between the seal element 20 and the mandrel 18. The annulus fluid may be directed to the chamber C formed between the seal element 20 and the mandrel 18, the pressurised annulus fluid impinging on the inner circumferential surface of the seal element 20 being used to urge or push the seal element 20 radially outwards into sealing or enhanced sealing engagement with the bore wall 14 (as shown in FIG. 5) and so provide a secondary activation of the seal element 20.

As shown most clearly in FIG. 2, annular end rings or gauge rings 22, 24 are provided at respective ends of the apparatus 10. The gauge rings 22, 24 have radially extending holes defining bores 26 for receiving grub screws (not shown). The bores 26 are provided in an annular portion 28 of the gauge rings 22, 24 which also have a tapered portion 30 at their distal ends.

In use, the seal element 20 and the ring 22 are arranged to permit the passage of the annulus fluid into the fluid-receiving chamber C.

In the illustrated embodiment, the gauge ring 22 also comprises axial passages or grooves 32 and, in use, the grooves 32 permit additional fluid communication with the fluid-receiving chamber C.

In the illustrated embodiment, the gauge ring 22 comprises eight grooves 32. However, it will be recognised that one groove 32 or a plurality of grooves 32 may be provided, as appropriate. Following initial activation of the apparatus 10, annulus fluid may be directed through the grooves 32 and into the chamber C, thereby providing an additional activation force which urges the seal element 20 into sealing engagement (where the seal element 20 is not already in sealing engagement with the bore wall 14 in the second configuration) or enhanced sealing engagement (where the seal element is already in sealing engagement with the bore wall 14 in the second configuration). While the illustrated embodiment provides for passage of fluid between the ring 22 and the chamber C and through the grooves 32, it will be recognised that fluid may be directed to the chamber C by one or both of these.

Referring now to FIG. 2 in particular, the apparatus 10 further comprises two further seal members, a first seal member 34 and a second seal member 36. The seal members 34, 36 are formed separately and bonded or moulded together and, in use, define the cup seal. The first seal member 34 is beneficially constructed from a material selected with high compliance to provide good sealing properties with the bore wall 14. The second seal member 36 beneficially is constructed from a material of greater hardness than the first seal member 34 and, in use, provides an anti-extrusion effect, preventing or mitigating extrusion of the seal element 20 and/or the seal members 34, 36.

In use, the seal element 20 is used to at least partially activate the further seal members 34, 36 by urging or pushing the seal members radially outwards to define the cup seal.

The apparatus 10 further comprises a back-up assembly 38 for supporting the seal members 34, 36 in maintaining sealing engagement with the bore wall 14.

The back-up assembly 38 comprises an annular ring member 40 mounted on the mandrel 18. A seal recess or groove 42 is provided on an inner surface 41 of the ring member 40, the seal groove 42 receiving a seal element in the form of a o-ring 44, although other seal elements may be used where appropriate. In use, the o-ring prevents fluid leakage between the ring member 40 and the mandrel 18.

The back-up assembly 38 further comprises a support member 46 which, in the illustrated embodiment, comprises a first back-up element 48 and a second back-up element 50. The first back-up element 48 has an annular portion 52 and a slotted portion defining a number of petals 54. The petals 54 extend over the end of the seal member 36 and bend or pivot radially outwards towards the bore wall 14 in use.

An annular insert or collar 56 is positioned on the mandrel 18 and is interposed between the support member 46 and the end of the seal member 36. In use, the collar 56 prevents damage to the support member 46 from seal member 36, in particular from axial forces transmitted through or generated in the seal member 36 during use and which may otherwise result in reduced performance, control or failure of the seal.

A seal recess or groove 58 is provided on an inner surface 60 of the collar 56, the seal groove 58 receiving a seal element in the form of a o-ring 62, although other seal elements may be used where appropriate. In use, the o-ring 62 prevents fluid leakage between the collar 56 and the mandrel 18 and, together with the seal element 20 provides the seal between the apparatus 10 and the bore wall 14.

Referring now in particular to FIGS. 3 to 5, in use, the apparatus 10 is run into the bore 16 with the seal element 20 defining a first, retracted, configuration (as shown in FIG. 3). In the first configuration as shown in FIG. 3, the seal element 20 defines a first volume.

The seal element 20 is then initially activated from the first configuration to the second, expanded, configuration (as shown in FIG. 4). In the second configuration, the seal element 20 defines a second, larger, volume. In the second configuration, pressurised fluid from the annulus 12 between the apparatus 10 and the bore wall 14 is utilised to provide a second stage activation in which the seal element 20 is urged into a third configuration in sealing or enhanced sealing engagement with the bore wall and the seal members 34, 36 form a cup (as shown in FIG. 5).

Referring now to FIGS. 6 to 10, there is shown a sealing apparatus 110 according to a second embodiment of the present invention, like components between the sealing apparatus 110 and the sealing apparatus 10 being represented by like numerals incremented by 100.

As with the apparatus 10, the apparatus 110 in the illustrated embodiment comprises a downhole cup seal packer for use in sealing an open or uncased hole and, in use, the apparatus 110 establishes a seal in an annulus 112 between the apparatus 110 and a wall (shown diagrammatically at 114 in FIG. 7 and in FIGS. 8 to 10) of a bore (shown diagrammatically at 116 in FIG. 7 and in FIGS. 8 to 10) which prevents passage of fluid along the annulus 112 in a selected direction, for example preventing passage of fluid in an uphole direction or in a downhole direction.

As shown in FIG. 6, the apparatus 110 comprises a mandrel 118 which forms part of a tubing string such as production conduit or the like (not shown). However, in order to show the other components of the apparatus 110, the mandrel 118 is not shown in FIGS. 7 to 10.

An annular seal element 120 is disposed around the mandrel 118, the seal element 120 comprising a swellable seal element which swells in response to a selected activation fluid in the annulus 112. In the illustrated embodiment, the seal element 120 is constructed from an oil-swellable elastomer and, in use, the seal element 120 may be run into the bore 118 in a first, retracted, configuration (as shown in FIG. 8) before being initially activated from the first configuration to a second, expanded, configuration when exposed to oil in the annulus 112 (as shown in FIG. 9).

The seal element 120 is disposed around the mandrel and is free to move radially relative to the mandrel 118 such that, in use, when the seal element 120 moves to the second configuration a fluid-receiving chamber C′ is defined between the seal element 120 and the mandrel 118. The annulus fluid may be directed to the chamber C′ formed between the seal element 120 and the mandrel 118, the pressurised annulus fluid impinging on the inner circumferential surface of the seal element 120 being used to urge or push the seal element 120 radially outwards into sealing or enhanced sealing engagement with the bore wall 114 and so provide a secondary activation of the seal element 120 (as shown in FIG. 10).

A gauge ring 122 is provided at an end of the apparatus 110.

As shown in FIG. 7, the gauge ring 122 and the seal element 120 comprise corresponding tapered surfaces 123, 125. In use, the tapered surfaces assist in directing radial movement of the seal element 120.

The gauge ring 122 has radially extending holes defining bores 126 for receiving grub screws (not shown). The bores 126 are provided in an annular portion 128 of the gauge ring which also has a tapered portion 130 at its distal uphole end (the left end as shown in the figures).

In use, the seal element 120 and the ring 122 are arranged to permit the passage of the annulus fluid into the fluid-receiving chamber C′.

In the illustrated embodiment, the gauge ring 122 also comprises axial passages or grooves 132 and, in use, the grooves 132 permit additional fluid communication with the fluid-receiving chamber C.

In the illustrated embodiment, the gauge ring 122 comprises eight grooves 132. However, it will be recognised that one groove 132 or a plurality of grooves 132 may be provided, as appropriate. Following initial activation of the apparatus 110, annulus fluid may be directed through the grooves 132 and into the chamber C′, thereby providing an additional activation force which urges the seal element 120 into sealing engagement (where the seal element 120 is not already in sealing engagement with the bore wall 114 in the second configuration) or enhanced sealing engagement (where the seal element is already in sealing engagement with the bore wall 114 in the second configuration). While the illustrated embodiment provides for passage of fluid between the ring 122 and the chamber C′ and through the grooves 132, it will be recognised that fluid may be directed to the chamber C′ by one or both of these.

Referring now to FIG. 7 in particular, the apparatus 110 further comprises two further seal members, a first seal member 134 and a second seal member 136. The seal members 134, 136 are formed separately and bonded or moulded together and, in use, define the cup seal. The first seal member 134 is beneficially constructed from a material selected with high compliance to provide good sealing properties with the bore wall 114. The second seal member 136 beneficially is constructed from a material of greater hardness than the first seal member 134 and, in use, provides an anti-extrusion effect, preventing or mitigating extrusion of the seal element 120 and/or the seal members 134, 136.

In use, the seal element 120 is used to at least partially activate the further seal members 134, 136 by urging or pushing the seal members 134, 136 radially outwards to define the cup seal.

As in the apparatus 10, the apparatus 110 comprises a back-up assembly 138 for supporting the seal members 134, 136 in maintaining sealing engagement with the bore wall 114. The back-up assembly 138 comprises an annular ring member 140 mounted on the mandrel 118. A seal recess or groove 142 is provided on an inner surface 141 of the ring member 140, the seal groove 142 receiving a seal element in the form of a o-ring 144, although other seal elements may be used where appropriate. In use, the o-ring prevents fluid leakage between the ring member 140 and the mandrel 118. The back-up assembly 138 further comprises a support member 146 which, in the illustrated embodiment, comprises a first back-up element 148 and a second back-up element 150. The first back-up element 148 has an annular portion 152 and a slotted portion defining a number of petals 154. The petals 154 extend over the end of the seal member 136 and bend or pivot radially outwards towards the bore wall 114 in use.

As can be seen from FIG. 7, the apparatus 110 further comprises a plurality of circumferentially spaced grooves or flutes 64. In use, the flutes 64 assist in passage of the fluid and increases the contact area between and/or the volume of fluid acting on the seal member 134.

Referring now in particular to FIGS. 8 to 10, in use, the apparatus 110 is run into the bore 116 with the seal element 120 defining a first, retracted, configuration (as shown in FIG. 8). In the first configuration as shown in FIG. 8, the seal element 120 defines a first volume.

The seal element 120 is then initially activated from the first configuration to the second, expanded, configuration (as shown in FIG. 9). In the second configuration, the seal element defines a second, larger, volume. In the second configuration, pressurised fluid from the annulus 112 between the apparatus 110 and the bore wall 114 is utilised to provide a second stage activation in which the seal element 120 is urged into a third configuration in sealing or enhanced sealing engagement with the bore wall and the seal members 134, 136 form a cup (as shown in FIG. 10).

It will be recognised that embodiments of the present invention thus provide a number of benefits. For example, embodiments of the present invention permit the creation and/or maintenance of a seal across the annulus of a bore of greater diameter, without the requirement for the seal element itself to expand to full bore diameter. Moreover, in instances where the bore wall is non-cylindrical and/or includes irregular or large diameter sections, such as where an area of the bore wall has collapsed or been washed out, embodiments of the present invention may beneficially permit the creation and maintenance of a reliable seal.

Embodiments of the present invention also provide for an initial activation of the seal element and a second activation which utilises the pressurised fluid in the annulus—which may otherwise cause extrusion of the seal element, reduce seal performance, make activation more difficult or risk failure of the seal—to maintain or enhance the seal with the bore wall. By utilising the pressurised fluid present in the annulus the use of applied activation forces—which may otherwise damage the surrounding bore wall or tubulars and increase the size and weight of the apparatus—may be obviated or reduced.

It should be understood that the embodiment described herein is merely exemplary and that various modifications may be made thereto without departing from the scope of the invention.

For example, while in the illustrated embodiments the seal element is initially activated from the first configuration to the second, expanded, configuration prior to being urged into sealing or enhanced sealing engagement with the wall of the bore, the seal element may alternatively be urged radially outwards simultaneously or subsequent to the initial activation.

While the illustrated embodiment describes apparatus for use in open hole, the apparatus may alternatively be used in a cased hole.

The apparatus may be utilised in any orientation.

While the seal element and seal members are described above at separate components, one or more of these may comprise a unitary component.

The apparatus may alternatively or additionally be configured so that the annulus fluid impinges on an end face of the seal element. In such embodiments, at least one of the seal element, the mandrel or other components of the apparatus may be formed or arranged to urge the seal element radially outwards in response to an axial force generated by the annulus fluid impinging on the end of the seal element. For example, at least one of the mandrel, seal element, first seal member may be tapered.

While in the illustrated embodiments, the initial activation may be taken up by expansion of the seal element, the apparatus may alternatively or additionally be configured to receive an initial applied activation force. The applied initial activation force may comprise an axial force, such as an axial compressive force. The apparatus may further comprise an activation arrangement for applying the initial activation force to the seal element. The activation arrangement may be of any suitable form or construction, and may comprise a setting tool or the like. The activation arrangement may form part of the apparatus. Alternatively, the activation arrangement may be provided separately from the apparatus. 

1. A sealing apparatus for use in establishing a seal in an annulus between a mandrel and a bore wall, the apparatus comprising: a mandrel; and a seal element disposed on the mandrel, the seal element configured to define a first configuration and a second, expanded, configuration, the apparatus configured so that fluid from the annulus acts on the seal element to urge at least part of the seal element radially outwards into sealing or enhanced sealing engagement with the bore wall.
 2. The apparatus of claim 1, wherein the first configuration comprises a retracted configuration.
 3. The apparatus of claim 1, wherein at least one of: the seal element comprises an annular seal element; the seal element is disposed around the mandrel; the apparatus comprises a plurality of the seal elements extending around the mandrel
 4. The apparatus of claim 1, wherein at least one of: the seal element is configured to expand in the presence of a selected activation medium; the activation medium comprises a fluid; the activation medium comprises fluid from the annulus between the apparatus and the bore wall.
 5. The apparatus of claim 6, wherein at least one of: the seal element comprises a material which swells in response to oil; the seal element comprises a material which swells in response to oil, wherein the seal element comprises an oil-swellable material, such as an oil-swellable elastomer; the seal element comprises a material which swells in response to water the seal element comprises a material which swells in response to water, wherein the seal element comprises a water swellable elastomer.
 6. The apparatus of claim 1, wherein at least one of: the apparatus is configured so that the seal element is moveable relative to the mandrel; the seal element is in sealing engagement with the mandrel.
 7. The apparatus of claim 1, wherein at least one of: the apparatus is configured so that, in the second configuration, the annulus fluid is directed between the seal element and the mandrel; the apparatus is configured so that, in the second configuration, the annulus fluid is directed between the seal element and the mandrel and the annulus fluid impinges on an inner circumferential surface of the seal element.
 8. The apparatus of claim 1, wherein at least one of: the apparatus is configured to define a fluid-receiving chamber between the seal element and the mandrel; the fluid-receiving chamber is present when the seal element is in the first configuration; the fluid-receiving chamber is formed when the seal element expands or moves from the first configuration to the second configuration.
 9. The apparatus of claim 1, wherein at least one of: the apparatus comprises a fluid passage configured to permit the passage of the pressurised fluid between the seal element and the mandrel; the fluid passage comprises an axially-extending fluid passage; the apparatus comprises a plurality of the fluid passages; the fluid passage is of hemi-cylindrical form; the apparatus comprises a plurality of the fluid passages and the fluid passages are of hemi-cylindrical form; the apparatus comprises a plurality of the fluid passages arranged circumferentially.
 10. The apparatus of claim 1, wherein at least one of: the apparatus is configured so that the seal element engages the bore wall in the second configuration; the apparatus is configured so that the seal element provides initial sealing engagement with the bore wall in the second configuration.
 11. The apparatus of claim 1, wherein at least one of: the apparatus defines a third configuration; the apparatus is configured so that the seal element is urged into sealing engagement with the bore wall in the third configuration; the seal element is configured to retain the third configuration.
 12. The apparatus of claim 1, wherein at least one of: the apparatus comprises at least one further seal member; the further seal member is configured to define a cup seal; the or each further seal member comprises at least one of: an elastomeric seal member; a compression seal member; a packing member; an expandable member; a swellable member; an oil-swellable member; a water-swellable member; an inflatable member, or any suitable style of seal member.
 13. The apparatus of claim 12, wherein at least one of: the apparatus comprises a single further seal member; the apparatus comprises a plurality of further seal members. the further seal members are of the same construction; the further seal members are of different construction; the further seal members are of different construction; the further seal members are selected and/or arranged in order to provide selected properties to the apparatus one or more further seal member comprises a material of greater hardness than one or more other seal member; the apparatus is configured so that the seal element activates the further seal member; the apparatus is configured so that the further seal member is at least partially activated by expansion of the seal element from the first configuration to the second configuration; the apparatus is configured so that the further seal member is at least partially activated when the seal element is urged from the second configuration to the third configuration.
 14. The apparatus of claim 1, wherein at least one of: the apparatus comprises one or more end ring; the apparatus comprises two end rings disposed at opposing ends of the apparatus; the fluid passage is formed in one of the end rings; at least one end ring comprises a radially-extending bore for receiving a retainer; each end ring comprises a plurality of radially-extending bores, each for receiving a retainer
 15. The apparatus of claim 1, wherein at least one of: the apparatus is configured so that part of the annulus fluid acts towards retaining the seal element on the mandrel; the apparatus is configured so that part of the annulus fluid acts towards retaining one or more further seal member on the mandrel.
 16. The apparatus of claim 1, wherein at least one of: the apparatus comprises a back-up assembly for supporting the seal element in maintaining sealing engagement with the bore wall.
 17. The apparatus of claim 1, wherein at least one of: the apparatus comprises a downhole packer; the apparatus comprises a uni-directional downhole packer; the apparatus comprises a cup seal packer.
 18. The apparatus of claim 1, wherein the apparatus is configured so the fluid from the annulus acts on the seal element when the seal element is in the second configuration.
 19. The apparatus of claim 1, wherein the seal element comprises a recess, groove or flute.
 20. A method comprising: providing an apparatus comprising a mandrel and a seal element for establishing a seal in an annulus between the mandrel and a wall of a bore; disposing the apparatus in the bore, activating the seal element from a first configuration to a second, expanded, configuration; and urging at least part of the seal element radially outwards into sealing engagement or enhanced sealing engagement with the wall of the bore using fluid from the annulus between the mandrel and the wall of the bore.
 21. The method of claim 20, wherein the seal element may be initially activated from the first configuration to the second configuration prior to being urged into sealing engagement or enhanced sealing engagement with the wall of the bore. 